Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect of a Change in Accounting Principle	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated Earnings	Accumulated Earnings Cumulative Effect of a Change in Accounting Principle	Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2017			47,577
Balance (in shares) at Dec. 31, 2017				(9,145)
Balance at Dec. 31, 2017	$ 554,341		$ 48	$ (185,074)	$ 585,755	$ 159,725		$ (6,113)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	37,729					37,729
Other comprehensive income (loss)	(4,741)							(4,741)
At the market offering, net of offering costs (in shares)			557
At the market equity offering, net of costs	39,567		$ 1		39,566
Share-based compensation	28,885				28,885
Issuance of common stock under employee stock plans (in shares)			1,346
Issuance of common stock under employee stock plans	30,611		$ 1		30,610
Tax payments related to restricted stock units	(6,775)				(6,775)
Balance (in shares) at Dec. 31, 2018			49,480
Balance (in shares) at Dec. 31, 2018				(9,145)
Balance at Dec. 31, 2018	679,617		$ 50	$ (185,074)	678,041	197,454		(10,854)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	61,338					61,338
Other comprehensive income (loss)	1,408							1,408
At the market offering, net of offering costs (in shares)			460
At the market equity offering, net of costs	37,806		$ 0		37,806
Share-based compensation	34,049				34,049
Issuance of common stock under employee stock plans (in shares)			1,337
Issuance of common stock under employee stock plans	40,706		$ 1		40,705
Tax payments related to restricted stock units	$ (9,670)				(9,670)
Balance (in shares) at Dec. 31, 2019	42,132		51,277
Balance (in shares) at Dec. 31, 2019	(9,145)			(9,145)
Balance at Dec. 31, 2019	$ 845,254	$ (264)	$ 51	$ (185,074)	780,931	258,792	$ (264)	(9,446)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Net income	$ 32,194					32,194
Other comprehensive income (loss)	3,924							3,924
Share-based compensation	44,697				44,697
Issuance of common stock under employee stock plans (in shares)			1,400
Issuance of common stock under employee stock plans	54,270		$ 2		54,268
Tax payments related to restricted stock units	(8,738)				(8,738)
Stock repurchases (in shares)				(749)
Stock repurchases	(53,035)			$ (53,035)
Equity component of convertible senior note issuance, net of issuance costs	97,830				97,830
Purchase of convertible note hedge	(100,625)				(100,625)
Sale of warrants	51,290				51,290
Tax benefits related to convertible senior notes and convertible note hedge	$ 706				706
Balance (in shares) at Dec. 31, 2020	42,783		52,677
Balance (in shares) at Dec. 31, 2020	(9,894)			(9,894)
Balance at Dec. 31, 2020	$ 967,503		$ 53	$ (238,109)	$ 920,359	$ 290,722		$ (5,522)